arch/powerpc/platforms/cell/cbe_cpufreq.c

   1 /*
   2  * cpufreq driver for the cell processor
   3  *
   4  * (C) Copyright IBM Deutschland Entwicklung GmbH 2005-2007
   5  *
   6  * Author: Christian Krafft <krafft@de.ibm.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2, or (at your option)
  11  * any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  21  */
  22
  23 #include <linux/cpufreq.h>
  24 #include <linux/of_platform.h>
  25
  26 #include <asm/machdep.h>
  27 #include <asm/prom.h>
  28 #include <asm/cell-regs.h>
  29 #include "cbe_cpufreq.h"
  30
  31 static DEFINE_MUTEX(cbe_switch_mutex);
  32
  33
  34 /* the CBE supports an 8 step frequency scaling */
  35 static struct cpufreq_frequency_table cbe_freqs[] = {
  36         {1,     0},
  37         {2,     0},
  38         {3,     0},
  39         {4,     0},
  40         {5,     0},
  41         {6,     0},
  42         {8,     0},
  43         {10,    0},
  44         {0,     CPUFREQ_TABLE_END},
  45 };
  46
  47 /*
  48  * hardware specific functions
  49  */
  50
  51 static int set_pmode(unsigned int cpu, unsigned int slow_mode)
  52 {
  53         int rc;
  54
  55         if (cbe_cpufreq_has_pmi)
  56                 rc = cbe_cpufreq_set_pmode_pmi(cpu, slow_mode);
  57         else
  58                 rc = cbe_cpufreq_set_pmode(cpu, slow_mode);
  59
  60         pr_debug("register contains slow mode %d\n", cbe_cpufreq_get_pmode(cpu));
  61
  62         return rc;
  63 }
  64
  65 /*
  66  * cpufreq functions
  67  */
  68
  69 static int cbe_cpufreq_cpu_init(struct cpufreq_policy *policy)
  70 {
  71         const u32 *max_freqp;
  72         u32 max_freq;
  73         int i, cur_pmode;
  74         struct device_node *cpu;
  75
  76         cpu = of_get_cpu_node(policy->cpu, NULL);
  77
  78         if (!cpu)
  79                 return -ENODEV;
  80
  81         pr_debug("init cpufreq on CPU %d\n", policy->cpu);
  82
  83         /*
  84          * Let's check we can actually get to the CELL regs
  85          */
  86         if (!cbe_get_cpu_pmd_regs(policy->cpu) ||
  87             !cbe_get_cpu_mic_tm_regs(policy->cpu)) {
  88                 pr_info("invalid CBE regs pointers for cpufreq\n");
  89                 return -EINVAL;
  90         }
  91
  92         max_freqp = of_get_property(cpu, "clock-frequency", NULL);
  93
  94         of_node_put(cpu);
  95
  96         if (!max_freqp)
  97                 return -EINVAL;
  98
  99         /* we need the freq in kHz */
 100         max_freq = *max_freqp / 1000;
 101
 102         pr_debug("max clock-frequency is at %u kHz\n", max_freq);
 103         pr_debug("initializing frequency table\n");
 104
 105         /* initialize frequency table */
 106         for (i=0; cbe_freqs[i].frequency!=CPUFREQ_TABLE_END; i++) {
 107                 cbe_freqs[i].frequency = max_freq / cbe_freqs[i].index;
 108                 pr_debug("%d: %d\n", i, cbe_freqs[i].frequency);
 109         }
 110
 111         /* if DEBUG is enabled set_pmode() measures the latency
 112          * of a transition */
 113         policy->cpuinfo.transition_latency = 25000;
 114
 115         cur_pmode = cbe_cpufreq_get_pmode(policy->cpu);
 116         pr_debug("current pmode is at %d\n",cur_pmode);
 117
 118         policy->cur = cbe_freqs[cur_pmode].frequency;
 119
 120 #ifdef CONFIG_SMP
 121         cpumask_copy(policy->cpus, cpu_sibling_mask(policy->cpu));
 122 #endif
 123
 124         cpufreq_frequency_table_get_attr(cbe_freqs, policy->cpu);
 125
 126         /* this ensures that policy->cpuinfo_min
 127          * and policy->cpuinfo_max are set correctly */
 128         return cpufreq_frequency_table_cpuinfo(policy, cbe_freqs);
 129 }
 130
 131 static int cbe_cpufreq_cpu_exit(struct cpufreq_policy *policy)
 132 {
 133         cpufreq_frequency_table_put_attr(policy->cpu);
 134         return 0;
 135 }
 136
 137 static int cbe_cpufreq_verify(struct cpufreq_policy *policy)
 138 {
 139         return cpufreq_frequency_table_verify(policy, cbe_freqs);
 140 }
 141
 142 static int cbe_cpufreq_target(struct cpufreq_policy *policy,
 143                               unsigned int target_freq,
 144                               unsigned int relation)
 145 {
 146         int rc;
 147         struct cpufreq_freqs freqs;
 148         unsigned int cbe_pmode_new;
 149
 150         cpufreq_frequency_table_target(policy,
 151                                        cbe_freqs,
 152                                        target_freq,
 153                                        relation,
 154                                        &cbe_pmode_new);
 155
 156         freqs.old = policy->cur;
 157         freqs.new = cbe_freqs[cbe_pmode_new].frequency;
 158         freqs.cpu = policy->cpu;
 159
 160         mutex_lock(&cbe_switch_mutex);
 161         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
 162
 163         pr_debug("setting frequency for cpu %d to %d kHz, " \
 164                  "1/%d of max frequency\n",
 165                  policy->cpu,
 166                  cbe_freqs[cbe_pmode_new].frequency,
 167                  cbe_freqs[cbe_pmode_new].index);
 168
 169         rc = set_pmode(policy->cpu, cbe_pmode_new);
 170
 171         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 172         mutex_unlock(&cbe_switch_mutex);
 173
 174         return rc;
 175 }
 176
 177 static struct cpufreq_driver cbe_cpufreq_driver = {
 178         .verify         = cbe_cpufreq_verify,
 179         .target         = cbe_cpufreq_target,
 180         .init           = cbe_cpufreq_cpu_init,
 181         .exit           = cbe_cpufreq_cpu_exit,
 182         .name           = "cbe-cpufreq",
 183         .owner          = THIS_MODULE,
 184         .flags          = CPUFREQ_CONST_LOOPS,
 185 };
 186
 187 /*
 188  * module init and destoy
 189  */
 190
 191 static int __init cbe_cpufreq_init(void)
 192 {
 193         if (!machine_is(cell))
 194                 return -ENODEV;
 195
 196         return cpufreq_register_driver(&cbe_cpufreq_driver);
 197 }
 198
 199 static void __exit cbe_cpufreq_exit(void)
 200 {
 201         cpufreq_unregister_driver(&cbe_cpufreq_driver);
 202 }
 203
 204 module_init(cbe_cpufreq_init);
 205 module_exit(cbe_cpufreq_exit);
 206
 207 MODULE_LICENSE("GPL");
 208 MODULE_AUTHOR("Christian Krafft <krafft@de.ibm.com>");